No loss, multi-band, adaptable antenna

Abstract

A no-loss, multi-band, adaptable Yagi style antenna employs a multi-element driven cell having a center element and one or more adjacent elements on each side of the center element. The adjacent elements of the driven cell are electrically shorter than the center element, thereby permitting the driven cell to be tuned to two or more frequency bands. The antenna is fed by a feedline connected to a common feed point at the center of the center element in the driven cell. Parasitic director elements are positioned in front of the driven cell and are tuned to the highest band of the driven cell. Parasitic reflector elements for one or more frequency bands are positioned behind the driven cell, with these elements tuned to actual operating frequencies of the antenna. The invention also provides a multi-band dipole antenna array covering three or more frequency bands comprising a set of dipole elements having a center element and one or more adjacent elements and one or more adjacent elements on each side of the center element. The adjacent elements are electrically shorter than the center element and are of unequal lengths. The antenna is fed by a feedline connected to a common feedpoint at the center of the center element of the set of dipole elements. Parasitic director elements are positioned in front of the set of dipole elements and parasitic reflector elements are positioned behind the set of dipole elements.

I claim: 
     
       1. A low loss antenna that is operable on at least three separate frequency bands comprising: a trapless driven element resonant at a single first frequency;   a first adjacent element adjacent to the driven element on a first side of the driven element, the first adjacent element being electrically shorter than the driven element, said first adjacent element spaced apart from the driven element and resonant at a second frequency at least 1.14 times the first frequency;   a second adjacent element adjacent to the driven element on a second side of the driven element, said second adjacent element being electrically shorter than the driven element and the first adjacent element, said second adjacent element spaced apart from the driven element and resonant at a third frequency less than 2.5 times the first frequency and at least 1.14 times the second frequency; and   a common feed point located at the driven element for coupling to a feedline for feeding signal energy to the driven element.   
     
     
       2. The low loss antenna as set forth in claim 1, wherein the driven element, first adjacent element and second adjacent element are dipole elements. 
     
     
       3. The low loss antenna as set forth in claim 2, further comprising at least one reflector positioned on a second side of the plurality of dipole elements opposite the first side. 
     
     
       4. The low loss antenna as set forth in claim 1, further comprising at least one director positioned on a first side of the driven element. 
     
     
       5. The low loss antenna as set forth in claim 4, further comprising at least one reflector positioned on a second side of the driven element opposite the first side. 
     
     
       6. The low loss antenna as set forth in claim 1, further comprising a least one multi-element director cell, each director cell comprising a center director element and at least one adjacent director element located on each side of the center director element, each of the adjacent director elements being electrically shorter than the center director element. 
     
     
       7. The low loss antenna as set forth in claim 6, wherein the length the driven and adjacent elements and the spacing between the center and adjacent elements are set so that the feed point impedance to the antenna is substantially similar to the characteristic impedance of the feedline. 
     
     
       8. The low loss antenna as set forth in claim 1, wherein the electrical length of the first adjacent element is at least 14% greater than the electrical length of the second adjacent element. 
     
     
       9. A low loss antenna comprising: a trapless driven element resonant at a single first frequency in a first frequency band;   a first adjacent element adjacent to the driven element on a first side of the driven element, said first adjacent element spaced apart from the driven element and resonant at a second frequency in a second frequency band, said second frequency being at least 1.14 times the first frequency;   a second adjacent element adjacent to the driven element on a second side of the driven element, said second adjacent element spaced apart from the driven element and resonant at a third frequency in a third frequency band, said third frequency being less than 2.5 times the first frequency and at least 1.14 times the second frequency; and   a common feed point located at the driven element for coupling to a feedline for feeding signal energy to the driven element.   
     
     
       10. The low loss antenna as set forth in claim 9, wherein the driven element, first adjacent element and second adjacent element are dipole elements. 
     
     
       11. The low loss antenna as set forth in claim 10, further comprising at least one reflector positioned on a second side of the plurality of dipole elements opposite the first side. 
     
     
       12. The low loss antenna as set forth in claim 9, further comprising at least one director positioned on a first side of the driven element. 
     
     
       13. The low loss antenna as set forth in claim 12, further comprising at least one reflector positioned on a second side of the driven element opposite the first side. 
     
     
       14. The low loss antenna as set forth in claim 9, further comprising a least one multi-element director cell, each director cell comprising a center director element and at least one adjacent director element located on each side of the center director element, each of the adjacent director elements being electrically shorter than the center director element. 
     
     
       15. The low loss antenna as set forth in claim 14, wherein the length of the driven and adjacent elements and the spacing between the center and adjacent elements are set so that the feed point impedance to the antenna is substantially similar to the characteristic impedance of the feedline. 
     
     
       16. The low loss antenna as set forth in claim 9, wherein the electrical length of the first adjacent element is at least 14% greater than the electrical length of the second adjacent element. 
     
     
       17. A low loss antenna comprising: a driven element resonant at a first frequency, not resonant at a second frequency, and not resonant at a third frequency;   a first adjacent element adjacent to the driven element on a first side of the driven element, said first adjacent element spaced apart from the driven element and resonant at the second frequency, not resonant at the first frequency, and not resonant at the third frequency; and   a second adjacent element adjacent to the driven element on a second side of the driven element, said second adjacent element spaced apart from the driven element and resonant at the third frequency, not resonant at the first frequency, and not resonant at the second frequency; and   a common feed point located at the driven element for coupling to a feedline for feeding signal energy to the driven element;   where the second frequency is at least 1.14 times the first frequency, the third frequency is at least 1.14 times the second frequency, and the third frequency is less than two and one-half times the first frequency.   
     
     
       18. The low loss antenna as set forth in claim 17, wherein the driven element, first adjacent element and second adjacent element are dipole elements. 
     
     
       19. The low loss antenna as set forth in claim 18, further comprising at least one reflector positioned on a second side of the plurality of dipole elements opposite the first side. 
     
     
       20. The low loss antenna as set forth in claim 17, further comprising at least one director positioned on a first side of the driven element. 
     
     
       21. The low loss antenna as set forth in claim 19, further comprising at least one reflector positioned on a second side of the driven element opposite the first side. 
     
     
       22. The low loss antenna as set forth in claim 17, further comprising a least one multi-element director cell, each director cell comprising a center director element and at least one adjacent director element located on each side of the center director element, each of the adjacent director elements being electrically shorter than the center director element. 
     
     
       23. The low loss antenna as set forth in claim 22, wherein the length of the driven and adjacent elements and the spacing between the center and adjacent elements are set so that the feed point impedance to the antenna is substantially similar to the characteristic impedance of the feedline. 
     
     
       24. The low loss antenna as set forth in claim 17, wherein the electrical length of the first adjacent element is at least 14% greater than the electrical length of the second adjacent element. 
     
     
       25. The low loss antenna as set forth in claim 17, whereby the antenna effectively radiates energy in three non-overlapping frequency bands. 
     
     
       26. The low loss antenna as set forth in claim 25, where the three non-overlapping frequency bands are chosen from United States amateur radio high frequency bands. 
     
     
       27. The low loss antenna as set forth in claim 17, where the driven element has a first half-power bandwidth, the first adjacent element has a second half-power bandwidth that does not overlap the first half-power bandwidth, and the second adjacent element has a third half-power bandwidth that does not overlap the first half-power bandwidth and does not overlap the second half-power bandwidth. 
     
     
       28. A low loss antenna that is operable on at least three separate frequency bands comprising: a trapless driven element resonant at a single first frequency selected from a range between 14.0 to 14.35 MHz;   a first adjacent element adjacent to the driven element on a first side of the driven element, the first adjacent element being electrically shorter than the driven element, said first adjacent element spaced apart from the driven element and resonant at a second frequency selected from a range between 21.0 to 21.45 MHz;   a second adjacent element adjacent to the driven element on a second side of the driven element, said second adjacent element being electrically shorter than the driven element, said second adjacent element spaced apart from the driven element and resonant at a third frequency selected from a range between 28.0 to 29.7 MHz; and   a common feed point located at the driven element for coupling to a feedline for feeding signal energy to the driven element.   
     
     
       29. A low loss antenna comprising: a trapless driven element resonant at a single first frequency in a first frequency band between 14.0 to 14.35 MHz;   a first adjacent element adjacent to the driven element on a first side of the driven element, said first adjacent element spaced apart from the driven element and resonant at a second frequency in a second frequency band between 21.0 to 21.45 MHz;   a second adjacent element adjacent to the driven element on a second side of the driven element, said second adjacent element spaced apart from the driven element and resonant at a third frequency in a third frequency band between 28.0 to 29.7 MHz; and   a common feed point located at the driven element for coupling to a feedline for feeding signal energy to the driven element.   
     
     
       30. A low loss antenna comprising: a driven element resonant at a first frequency between 14.0 and 14.35 MHz, not resonant at a second frequency between 21.0 and 21.45 MHz, and not resonant at a third frequency between 28.0 and 29.7 MHz;   a first adjacent element adjacent to the driven element on a first side of the driven element, said first adjacent element spaced apart from the driven element and resonant at the second frequency, not resonant at the first frequency, and not resonant at the third frequency; and   a second adjacent element adjacent to the driven element on a second side of the driven element, said second adjacent element spaced apart from the driven element and resonant at the third frequency, not resonant at the first frequency, and not resonant at the second frequency; and   a common feed point located at the driven element for coupling to a feedline for feeding signal energy to the driven element.   
     
     
       31. A low loss antenna that is operable on at least three separate frequency bands comprising: a trapless driven element resonant at a single first frequency that is substantially 10.1 MHz;   a first adjacent element to the driven element on a first side of the driven element, the first adjacent element being eletrically shorter than the driven element, said first adjacent element spaced apart from the driven element and resonant at a second frequency that is substantially 18.1 MHz;   a second adjacent element adjacent to the driven element on a second side of the driven element, the second adjacent element being electrically shorter than the driven element, said second adjacent element spaced apart from the driven element and resonant at a third frequency that is substantially 24.9 MHz; and   a common feed point located at the driven element for coupling to a feedline for feeding signal energy to the driven element.   
     
     
       32. A low loss antenna comprising: a trapless driven element resonant at a single first frequency in a first frequency band between 10.1 to 10.15 MHz;   a first adjacent element adjacent to the driven element on a first side of the driven element, said first adjacent element spaced apart from the driven element and resonant at a second frequency in a second frequency band between 18.068 to 18.168 MHz;   a second adjacent element adjacent to the driven element on a second side of the driven element, said second adjacent element spaced apart from the driven element and resonant at a third frequency in a third frequency band between 24.89 to 24.99 MHz; and   a common feed point located at the driven element for coupling to a feedline for feeding signal energy to the driven element.   
     
     
       33. A low loss antenna comprising: a driven element resonant at a first frequency between 14.0 and 14.35 MHz, not resonant at a second frequency between 21.0 and 21.45 MHz, and not resonant at a third frequency between 28.0 and 29.7 MHz;   a first adjacent element adjacent to the driven element on a first side of the driven element, said first adjacent element spaced apart from the driven element and resonant at the second frequency, not resonant at the first frequency, and not resonant at the third frequency; and   a second adjacent element adjacent to the driven element on a second side of the driven element, said second adjacent element spaced apart from the driven element and resonant at the third frequency, not resonant at the first frequency, and not resonant at the second frequency; and   a common feed point located at the driven element for coupling to a feedline for feeding signal energy to the driven element.